An electrooptic intensity modulator with improved linearity

A highly linear electrooptic modulator has been designed, fabricated, and evaluated. The design of this modulator consists of only a simple modification to the directional coupler. Two-tone testing has demonstrated that, for an optical modulation depth of 30% per channel, the third-order intermodulation distortion is more than 30 dB lower than that of the conventional directional coupler or Mach-Zehnder modulators. This improvement was not observed to be accompanied by any increase in second harmonic distortion. Also included are results of two-tone computer simulations which predict the improvement in linearity of this device for a range of modulation depths.<>     

All fiber 2/spl times/2 polarization insensitive switch

We report the development of a polarization insensitive all fiber 2/spl times/2 acoustooptic switch based on twisting the waist of a null taper coupler. The polarization insensitivity is better than 0.2 dB, the device requires a drive power of <1 mW, and exhibits a switching time of <50 /spl mu/s and insertion loss of 0.1 dB.     

Fourier-transform Raman spectra of ivory. III: Identification of mammalian specimens

The FT-Raman spectra of six mammalian ivories, other than elephant and mammoth, are presented and spectral differences formulated into a protocol for the identification of animal species from the ivory samples. In this study, sperm whale, walrus, wart hog, narwhal, hippopotamus and domestic pig are considered. The results, which are obtained non-destructively from a variety of specimens, suggest that FT-Raman spectroscopy provides a potentially useful method for the identification of mammalian ivory.     

Increased linear dynamic range by low biasing the Mach-Zehndermodulator

Operating a Mach-Zehnder modulator at an optical bias below the conventional 50% (quadrature) bias is investigated. Theoretical distortion curves as a function of bias have been calculated and experimentally verified. These curves show that (single octave) linear dynamic range increases as the bias is lowered, so long as optical power at the detector can be maintained just below the saturation level or laser noise limit. This method thus provides a way for very large optical power to be used to benefit linear dynamic range. Theoretically, 20 dB of excess optical power, attenuated through low biasing, can result in an increase in linear dynamic range of 15 dB     

A NEW PARADIGM FOR IS

An Is paradigm shift will create problems of adjustment and new opportunities for IS professionals. To function effectively in this new world, current and future IS professionals must acquire new knowledge and skills. This will not be easy to accomplish and will require the joint effort of both industry and academia. However, the payoffs from such human investments will be enormous. The existence of a cadre of capable IS professionals who can intelligently and effectively apply emerging information technologies not only affects the success of individual organizations but improves the competitiveness of our nation.     

Increased disruption of sperm plasma membrane at sperm immobilization promotes dissociation of perinuclear theca from sperm chromatin after intracytoplasmic sperm injection in pigs

The effects of sperm-immobilization methods on decondensation of sperm chromatin and retention of subacrosomal sperm perinuclear theca (SAR-PT) after intracytoplasmic sperm injection (ICSI) were examined in pigs. Sperm membrane damage caused by different immobilization methods by rubbing with a micropipette without piezo pulses (R), or with a low (L) or high (H) intensity of piezo pulses while rubbing, was assessed by the time required for staining of sperm heads with eosin Y solution. The average time for staining of sperm heads immobilized by the R, L or H treatments was 76, 41 or 26 s, respectively. The fertilization rate following ICSI was increased by sperm immobilization by piezo pulses compared with R, but increased intensity of pulses from L to H did not cause further improvements (29, 48 and 47%, respectively). An immunofluorescence study revealed that H immobilization promoted the dissociation of SAR-PT from sperm chromatin compared with L and R, and it increased the frequency of male pronuclear formation in which chromatin appeared uniformly decondensed. With in vitro fertilization (IVF), SAR-PT disassembled coordinately with sperm chromatin decondensation and it was not detectable around male pronuclei. This was different from most of the oocytes after ICSI in which remnants SAR-PT were detected adjacent to male pronuclei. We concluded that increased damage on the sperm plasma membrane at immobilization improved fertilization rates and decondensation of sperm chromatin after ICSI due to the accelerated dissociation of SAR-PT from the sperm nucleus. Also, the behavior of SAR-PT after ICSI was different from that observed in oocytes after IVF.     

Resonant loop mirror with narrow-band reflections and its application in single-frequency fiber lasers

We present a new form of loop mirror (to be realized with all-fiber or integrated optics technology) that can produce narrow-band reflections and could find an application in single-frequency fiber lasers, allowing for a standing-wave design with a long doped section and eliminating the need for a Faraday isolator or a fiber grating. We discuss the main features of such a loop mirror and present experimental results that agree well with the theory.     

Design and Performance of an Integrated Analytical Swatch Testing System

Abstract

An integrated swatch testing system for precisely quantifying the resistance of chemical protective materials to permeation and penetration by a chemical weapons agent (CWA) simulant is described. The analytical variability of methodologies currently used by Department of Defense testing laboratories was dramatically reduced by modifying the test cell and experimental procedures while maintaining compatibility with military testing specifications. Utilizing an on-line calibration system, cryogen-free preconcentrator, and flame ionization detector, the integrated system has demonstrated excellent repeatability, reproducibility, and high sampling frequency for a variety of non-porous and air-penetrable swatch samples challenged with methyl salicylate.     

3/spl times/3 all-fiber routing switch

An all-fiber acoustooptic switch has been constructed from a 3/spl times/3 null fused coupler. The maximum drive power required is 4 mW, the switching time is 100 /spl mu/s and the insertion loss is less than 0.5 dB and has a cross talk of 20 dB. The switch shares the advantages of an earlier 2/spl times/2 switch but with more fiber ports, and should permit the design of compound routing arrays with fewer switching elements per channel.